when converting an CHM file to epub some of the pages were not converted at all, that is to say there were missing from the final file.

When converting the same CHM to EPUB (default options in both cases BTW as I don't understand the option enough [yet?] to play around with them) some pages - possibly the one containing more non-text parts than others -were converted in such a way that made it impossible to enlarge the font on my Sony PRS-300 to make it readable-change of font size doesn't change anything in the display.... I can enlarge the font on other pages just fine...
Is this something that can be overcome by changing the conversion options? If so, please advise what/how to change.